1. Field of the Invention
The present invention relates to the field of fluid dynamic bearing assemblies of the type that cooperate with high-speed spindle elements. More specifically, the invention relates to restricting the tilting distance between rotating and stationary members of bearing assemblies utilized in a disc drive system.
2. Description of the Related Art
Disc drive memory systems have been used in computers for many years for the storage of digital information. Digital information is recorded on concentric memory tracks of a magnetic disc medium in the form of magnetic transitions within the medium. The discs themselves are rotatably mounted on a spindle. The information is accessed by means of read/write heads generally located on a pivoting arm that moves radially over the surface of the disc. The read/write heads or transducers must be accurately aligned with the storage tracks on the disc to ensure proper reading and writing of information.
During operation, the discs are rotated at very high speeds within an enclosed housing by means of an electric motor generally located inside a hub that supports the discs. One type of motor in common use is known as an in-hub or in-spindle motor. Such in-spindle motors typically have a spindle mounted by means of two ball or hydrodynamic bearing systems to a motor shaft disposed in the center of the hub. Generally, such motors include a stator comprising a plurality of teeth arranged in a circle. Each of the teeth support a plurality of coils or windings that may be sequentially energized to polarize the stator. A plurality of permanent magnets are disposed in alternating polarity adjacent the stators. As the coils disposed on the stators are sequentially energized in alternating polarity, the magnetic attraction and repulsion of each stator to the adjacent magnets cause the spindle to rotate, thereby rotating the disc and passing the information storage tracks beneath the head.
The use of hydrodynamic bearing assemblies in such drive systems has become preferred due to desirable reductions in drive size and noise generation as compared to conventional ball bearing drive systems. In hydrodynamic bearings, a lubricating fluid, such as oil or air, functions as the bearing surface between a stationary base or housing and a rotating spindle or hub. The lubricating fluid requires gaps between the stationary and rotating members in order to provide the support, stiffness and lubricity required for proper bearing operation.
These gaps between the stationary and rotating members of the bearing may permit the rotating member to become tilted with respect to the stationary member. This tilting of the rotating member within the gaps may create contact points between the rotating and stationary bearing members. Such contact points may wear down the surfaces on both the rotating and stationary members at the points of contact enlarging the gap therebetween and undesirably affecting the performance of the bearing by creating particles.
Therefore, there is a need in the art for restricting the tilting distance between rotating and stationary members of bearing assemblies utilized in disc drive systems.